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Browsing by Author "Giridhar, S"

Browsing by Author "Giridhar, S"

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  • Hanle echelle spectrograph: design and performance 
    Sriram, S; Amit Kumar; Arun Surya; Sivarani, T; Giridhar, S; Kathiravan, S; Anand, M. N; Jones, D; Grobler, D; Jakobsson, R; Anantha, Ch; Athira Unni; Angchuk, D; Tsewang, D; Gyalson, T (SPIE-The International Society for Optical Engineering, 2018-07-06)
    Hanle echelle spectrograph (HESP) is a high resolution, bench mounted, fiber-fed spectrograph at visible wavelengths. The instrument was recently installed at the 2m Himalayan Chandra Telescope (HCT), located at Indian ...
  • HD 34700: A new T Tauri double-lined spectroscopic binary 
    Arellano, F. A; Giridhar, S (The European Southern Observatory, 2003-09)
    We find the star HD 34700 to be a double-lined spectroscopic binary. We also identify it as a weak-line T Tauri object. The spectra of both components are very similar and both show the Li I feature at 6708 Å. Strong ...
  • The He II 5411 Å velocity curve of the Wolf-Rayet eclipsing system HD 214419 
    Giridhar, S (Indian Institute of Astrophysics, 1978)
    A velocity curve of the Wolf-Rayet eclipsing system HD 214419 is obtained from measures on prismatic spectra of the Hell 5411 emission line. The shape of the velocity curve is unlike that obtained for Hell 4686. The emission ...
  • High resolution spectroscopy of R Coronae Borealis during the 1988-1989 minimum 
    Lambert, D. L; Kameswara Rao, N; Giridhar, S (Indian Academy of Sciences, 1990-12)
    Moderate-resolution spectra of the C2 Swan 0-1 bandhead, the Na I D lines and the K I resonance lines near 7660 A obtained at minimum light during the 1988-1989 decline of R CrB are discussed and interpreted in terms of a ...
  • High Resolution Spectroscopy of the Semi-Regular Variable LR Sco 
    Giridhar, S; Kameswara Rao, N; Lambert, D. L (Indian Academy of Sciences, 1992)
    A detailed spectroscopic investigation of LR Sco which was earlier misclassified as R CrB star is made. Atmospheric parameters and elemental abundances are determined using detailed depth-dependent model atmospheres and ...
  • High resolution spectroscopy with a 10-m class telescope 
    Giridhar, S (Astronomical Society of India, 2000)
  • The hot R Coronae Borealis star DY Centauri: Nebular and photospheric lines 
    Kameswara Rao, N; Giridhar, S; Lambert, D. L (The European Southern Observatory, 1993-12)
    High resolution spectra in the red region of the hot R CrB star DY Cen show the following characteristics: a strong absorption line spectrum dominated by lines of C II, N II, and Ne I inverse P-Cygni type profiles of some ...
  • Identification of metal-poor stars using the artificial neural network 
    Giridhar, S; Goswami, A; Kunder, A; Muneer, S; Selvakumar, G (EDP Sciences, 2013-08)
    Context. Identification of metal-poor stars among field stars is extremely useful for studying the structure and evolution of the Galaxy and of external galaxies. Aims. We search for metal-poor stars using the artificial ...
  • Image processing facilities at Vainu Bappu observatory 
    Giridhar, S; Bhattacharyya, J. C; Kutty, K. N (Tata Institute of Fundamental Research, 1988)
    Need for application of Image processing techniques in astronomical studies in optical wavelengths and special advantages accruing thereby are discussed. The paper describes various image processing facilities that are ...
  • Important parameters of four small-amplitude cepheids from uvby photometry 
    Arellano Ferro, A; Giridhar, S; Parrao, L (Konkoly Observatory, 1987-08)
  • An internally consistent set of oscillator strengths for Fe I lines 
    Giridhar, S; Ferro, A. A (Indian Academy of Sciences, 1989-03)
    An extensive set of internally consistent oscillator strength values for Fe I lines is compiled using literature data and scaling the oscillator strengths derived by different workers to that of Blackwell and his coworkers. ...
  • Investigation of variable star candidates in the globular cluster NGC 5024 (M53) 
    Bramich, D. M; Arellano Ferro, A; Figuera Jaimes, R; Giridhar, S (Wiley-Blackwell, 2012-08)
    We have performed a careful investigation of the 74 candidate variable stars presented by Safonova & Stalin. For this purpose we used our data base of imaging and light curves from Arellano Ferro et al. We find that two ...
  • Is LR SCO and RCB star? 
    Giridhar, S; Kameswara Rao, N; Lambert, D. L (The Observatory, 1990-08)
  • Is the Post-AGB Star SAO 40039 Mildly Hydrogen-Deficient? 
    Sumangala Rao, S; Pandey, G; Lambert, D. L; Giridhar, S (IOP Publishing, 2011-08-10)
    We have conducted an LTE abundance analysis for SAO 40039, a warm post-AGB star whose spectrum is known to show surprisingly strong He I lines for its effective temperature and has been suspected of being H-deficient and ...
  • A Li-rich post-AGB star HD 172481 
    Giridhar, S; Arellano Ferro, A; Mathias, P (Astronomical Society of India, 2001)
    Our abundance analysis of this post-AGB candidate star confirms that the HD 172481 is indeed a post-AGB star. It belongs to an important, but relatively rare class of post-AGB stars showing Li I features in their spectra. ...
  • A new discussion on the M(v) - W(O I 7774 A) relationship for F-G stars in the light of high-resolution data 
    Arellano Ferro, A; Giridhar, S; Goswami, A (Royal Astronomical Society, 1991-05)
    High-resolution CCD data and a large group of F-G stars of fundamentally determined distances are used here to investigate the intrinsic nature of the M(v) - W(O I) relation and the effect of other atmospheric parameters ...
  • A new search for variable stars in the globular cluster NGC 6366 
    Ferro, A. A; Giridhar, S; Lopez, V. R; Figuera, R; Bramich, D. M; Rosenzweig, P (Instituto de Astronomía, 2008-10)
    New CCD photometry of NGC 6366 has lead to the discovery of some variable stars. Two possible Anomalous Cepheids (or Pop II Cepheids), three long period variables, one SX Phe and one eclipsing binary have been found. Also, ...
  • A new study of the variable star population in the Hercules globular cluster (M13; NGC 6205) 
    Deras, D; Arellano Ferro, A; Lazaro, C; Bustos Fierro, I. H; Calderon, J. H; Muneer, S; Giridhar, S (Oxford University Press on behalf of the Royal Astronomical Society, 2019-06)
    We present the results from VI CCD time-series photometry of the globular cluster M13 (NGC 6205). From the Fourier decomposition of the light curves of RRab and RRc stars we found an average metallicity of [Fe/H]zw = −1.58 ...
  • New variables in M5 (NGC 5904) and some identification corrections 
    Arellano Ferro, A; Bramich, D. M; Giridhar, S; Luna, A; Muneer, S (Konkoly Observatory, 2015-04)
    We report twelve variables not previously detected in the globular cluster M5 (NGC 5904); one SX Phe and eleven semi-regular variables (SR). Their identifications, equatorial coordinates, ephemerides, and light curves are ...
  • NGC 6712: the variable star population of a tidally disrupted globular cluster 
    Deras, D; Arellano Ferro, A; Lazaro, C; Bustos Fierro, I. H; Calderon, J. H; Muneer, S; Giridhar, S (Oxford University Press on behalf of the Royal Astronomical Society, 2020-04)
    We present an analysis of VI CCD time-series photometry of globular cluster NGC 6712. Our main goal is to study the variable star population as indicators of the cluster mean physical parameters. We employed the Fourier ...

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